Liquid pump for deep wells



Dec. 28, 1965 D, R WN 3,225,697

LIQUID PUMP FOR DEEP WELLS Filed March 1, 1962 3 Sheets-Sheet 1 2e a W 143 ffi/ ,4 T g' 44 A 34 4o 37 22 15k 7 38 7% A /|i 35 4:2! 4 i 36 "I 5 52| as 7 INVENTOR KENARD D. BROWN ATTORNEYS Dec. 28, 1965 ow 3,225,697

LIQUID PUMP FOR DEEP WELLS Filed March 1. 1962 3 Sheets-Sheet 2INVENTOR.

KENARD D. BROWN ATTORNEYS Dec. 28, 1965 K. D. BROWN LIQUID PUMP FOR DEEPWELLS 3 Sheets-Sheet 3 Filed March 1. 1962 E Y9 m, 6 32% m 'l I i 0 all76 6 D GG Q 6% INVENTOR. KENARD D. BROWN BY Z7 5 ATTORNEYS United StatesPatent 3,225,697 LIQUID PUMP FOR DEEP WELLS Kenard D. Brown, Denver,Colo. (1227 S. Willow St., Casper, Wyo.) Filed Mar. 1, 1962, Ser. No.176,594 12 Claims. (Cl. 103-25) This invention relates to liquid pumpsand particularly to an improved pump for facilitating the production ofliquid petroleum or other liquids from deep wells.

The formation pressures and liquid flow rates in many oil wells are suchthat the oil may be produced only by pumping. Even in relatively shallowwells difficulties are encountered in the continuous production of oil.Furthermore, when production rates are low the pumping operation becomescorrespondingly uneconomical; the motors driving conventional pumps arerequired to lift the weight of the iron sucker rod which actuates thepump on a low production short cycling and overloading of the motors mayresult.

Another troublesome difficulty is encountered in conventional pumpoperation when gas is present with the oil and accumulates in the pumpcylinder sufliciently to cause gas locking. Gas locking is the result ofgas in the cylinder at suflicient pressure to prevent the spring pressedintake valves from opening; the piston thus operates with a volume ofgas in the cylinder which remains there and prevents the further intakeof fluids thereby rendering the pump ineffective.

Further difliculties are encountered which arise from the pressure ofgas in the formation which is released upon the reduction of pressureresulting from operation of the pump; this gas release produces coolingof the formation liquids and paraflin, asphalt and other solids may beformed. Such solids tend to seal or plug the formation and greatlyreduce the flow of fluids therethrough.

It is an object of the present invention to provide an improved liquidpump for oil wells and the like and which may be operated substantiallyat reservoir formation pressure.

It is another object of this invention to provide a liquid pump for deepwell operation and the like including an improved arrangement forfacilitating the production of liquid for low production wells.

It is another object of this invention to provide an improved liquidpump for oil wells and the like which is not subject to gas lockingduring production of oil from gas bearing formations.

It is another object of this invention to provide a liquid pump for oilwells and the like including an improved control system for effectingreliable and economical operation thereof.

It is a further object of this invention to provide an improved liquidpump of simple and rugged construction for facilitating the productionof liquids from deep wells.

It is a still further object of this invention to provide an improvedliquid pump for effecting economical production of oil from lowproduction wells.

It is still another object of this invention to provide an improvedliquid pump for oil wells and the like which may be easily installed ina well casing and does not necessitate the use of a separate productiontube.

It is an additional object of this invention to provide a liquid pumpfor deep wells and the like including :an improved and simplearrangement for changing the capacity of the pump per stroke of thepiston. 4 Briefly, in carrying out the objects of this invention in oneembodiment thereof, an elongated pump body of a size readily introducedinto a well or well casing is arranged to be positioned in a well andheld adjacent the formation to beproduced, -An elongated cylinder isprovided in the body and a piston is mounted for free movement in thecylinder, a piston rod extending up through the body for operation of.the piston. The intake and discharge valves are arranged in the bodynear the top of the cylinder; the intake valves are of a normally opentype.

When the piston is in an upper position in the cylinder and the pistonrod is released, the piston descends and formation fluids enter thecylinder through the open intake valves. When a predetermined weight ofliquid has been accumulated the pump control starts the motor at thewell head and lifts the piston to discharge the liquid from thecylinder. The pump may be operated by a flexible line, because thepiston does not require power on its downstroke. The control systemincludes sensing devices responsive to the weight of accumulated liquidin the cylinder, a flow responsive device, and may also includearrangements for predetermining the length of stroke of the piston, aswell as limit controls for preventing excessive movement thereof. Otherembodiments include arrangements employing production tubes,arrangements for sealing off a portion of the well casing and producingthe liquid through the casing, and ar rangements for effecting readyrelease and removal of the pump from the well.

The features of novelty which characterize the invention are pointed outwith particularity in the appended claims; the invention itself,however, both as to its organization and manner of operation, togetherwith fur ther objects and advantages thereof will be better understoodfrom the following description taken in connection with the accompanyingdrawings in which:

FIG. 1 is a somewhat diagrammatic elevation view, partly in section andpartly broken away, of a pump em bodying the invention;

FIG. 2 is a diagrammatic elevation view of a pumping equipment installedin a well and illustrating the control system embodying the inventionand employed with a lprligplof essentially the same construction as thatof FIG. 3 illustrates diagrammatically a strain gauge $18113 responsivecontrol suitable for use in the system of FIG. 4 is a view similar tothat of FIG. 2, with the downhole portions not shown, illustratinganother embodiment of the power apparatus and control system;

FIG. 5 is an enlarged plan view of a portion of the system of FIG. 4;and

FIG. 6 is a view of a portion of a rig similar to those shown in FIGS. 2and 4 illustrating a further embodiment of the control system.

Referring now to the drawings, FIG. 1 illustrates the pump of thisinvention positioned at the bottom of a Well within a casing 10 having amultiplicity of perforations 11 for communication with the producingportion of the reservoir formation. The pump comprisesa cylindrical mainbody portion 12 having a bottom closure cap 13 and a top cap or header14 providing a closed pump chamber indicated generally at 15. The pumprests on the bottom of the well indicated at 16 on a foot 17 connectedto the bottom cap 13 by a rod 18, the length of which is adjusted toposition the pump at the required elevation from the bottom 16.

The head 14 is provided with a plurality of normally open inlet valves20 and a plurality of normally closed discharge valves 21. A cylindricalriser 22 of reduced diameter as compared with the cylinder 12 extendsupwardly from the head 14 and encompasses the discharge valves 21. Areciprocable piston 23 is provided-in the cylinder 15 and is connectedto a suitable lifting mechanism by a piston rod 24 which passes througha packing 25 in the head 14 and extends upwardly above the riser 22 andterminates in a threaded end 26 or other suitable connecting element.

The pump cylinder or body 12 is centered in the wall casing 11 by aplurality of flexible stabilizers 27 and the extension 22 is providedwtih a swab cup 28 of flexible rubber-like material which centers theextension 22 in the casing and seals the extension to the casing toseparate the area above the swab cup from the area below which surroundsthe pump and to which fluids are admitted from the formation through theholes 11. The head 13 is connected to the lower end of the cylindricalpump casing 12 by threads as indicated at 29 and the head 14 issimilarly connected to the upper end of the cylindrical casing bythreads 31. The pump body 12 is constructed in two portions asindicated, these portions being separated by threads 32 so that thelower portion between the threads 29 and 32 may readily be replaced byother portions of varying lengths so that the stroke capacity of thepump may easily be changed by insertion of different lengths of casing.

In a similar manner the extension 22 is connected to the head 14 by athreaded connection 33 and is made in two portions, an upper portion 34and a central portion 35 connected by threaded connection 36. The upperportion 34 of extension 22 is provided with a plurality of ports 37providing communication between the inner and outer walls of the portion34 and which are closed by a slide valve or sleeve 38 having an annularshoulder 39 engaging a shoulder 40 formed on the inner circumference ofthe upper portion 34. The sleeve 38 is biased downwardly by a pluralityof compression springs one of which is indicated at 41 and which arepositioned between the upper end of the sleeve and a groove or seat 42formed in an enlarged top portion of the extension 22; this top portionis indicated at 43 and is threadedly connected to the portion 34 asindicated at 44. The sleeve valve 38 is provided with ports 45 which arearranged to register with the ports 37 when the sleeve is movedupwardly. This provides an arrangement for equalizing the pressure aboveand below the swab cup 28 so that after equalization of pressures theentire assembly may readily be lifted from its position within thecasing.

In order to actuate the sleeve valve and move the ports 45'into registrywith the ports 37, a multiple radial arm assembly or spider 46 isrigidly secured to the piston rod 26 within the extension 22. The armsof the assembly are spaced to provide ample free area for the passage offluids through the extension. The spider is positioned so that, when thepiston is moved upwardly to an extreme position, the spider will engagethe sleeve 38 and will lift the sleeve against the weight of the pumpassembly until the sleeve moves upwardly and the shoulder 40 engages thebottom inner edge of the top portion 43 which acts as a stop. Thereuponfurther movement of the sleeve is prevented and the entire assembly islifted from the position in the well, the swab cup being released sothat it slides readily upon equalization of the pressure through theports thus opened in registry.

The pump is controlled and operated so that power is applied solely onthe upstroke. When the piston rod 26 is released and allowed to descendby its own weight, fluids pour into the cylinder through the normallyopen intake valves and the piston moves downwardly to its lowermostnormal position. In order to limit the extreme movements of the pistonthe pump as shown in FIG. 1 has been provided with a lower limit switch47 and an upper limit switch 48, which switches are engaged and actuatedby the piston 23 in its lowermost and uppermost positions, respectively,to prevent further movement toward the ends of the cylinder. When thelower limit switch 47 is closed the power control apparatus (not shown)is actuated to stop the downward movement of the lifting mechanism. Whenthe piston reaches its extreme upper position as determined by theposition of the limit switch 48, this switch is closed and the controlapparatus is actuated to release the piston and allow it again todescend in the chamber 15.

The portion of the cylinder below the piston 23 and indicated at 15normally contains gas, and possible other fluids due to leakage past thepiston, and this gas is rarefied when the piston rises thereby producinga low pressure in the portion of the cylinder below the piston. This lowpressure facilitates the quick return of the piston when the mechanismis released to allow it to descend. In order to prevent the undueaccumulation of fluids and particularly liquids below the piston, acheck valve 51 is provided in the bottom cap 13 through which liquidsaccumulating in the chamber 15 below the piston will be released whenthe piston reaches its lower position provided they are in excessquantity. In addition a valve 51 is provided to release liquid at excesspressure from the top chamber 15 at the top of the piston to the chamber15' below the piston, this being a safety provision for abnormalconditions of operation.

During normal operation of the pump illustrated in FIG. 1, a controlsystem is provided which actuates the piston so that it moves betweenpositions intermediate the limit switches 47 and 48, these switchesbeing provided solely to actuate the control in the event of excessivemovement of the piston 23. The control system employed with the pump isarranged to actuate the power equipment to raise the piston 23 anddischarge liquid from'the pump when a predetermined quantity of liquidhas accumulated above the piston within the chamber 15. By this controlthe pump is operated only when the predetermined quantity of liquid hasaccumulated and thus power is employed only when the pump hasaccumulated an effective quantity of liquid, and economy in operation issecured. A pump of this type may thus be employed in low productionwells and may, for example, complete only one stroke in a period of oneday or more. In other applications it may, of course, be operated atgreater frequency, the frequency of operation depending solely on therate at which liquid is available. The control and the manner in whichit operates are described below.

The pump as constructed in FIG. 1 will, of course, receive any gaspresent in the formation at the intake valves 20. This gas which flowsinto the pump is discharged ahead of the liquid on the rise of thepiston and there can be no gas locking of the pump. In the event ofexcessive pressure within the formation, gas will move directly throughthe intake and discharge valves. And whenever liquid accumulates in thecasing 10 about the pump and above the intake valve 20, the liquid willflow into the chamber 15 to the exclusion of gas which may rise andaccumulate within the zone of the casing 10 above the intake valve andbelow the swab cup 28.

A control system embodying the invention and suitable for the operationof the pump of FIG. 1 is illustrated in FIGS. 2 and 3. In thisapplication the pump of FIG. 1 is employed with the supporting pedestal17 and rod 18 removed and with the upper extension 22 replaced by astring of conventional production tubing 50. In this system the pump isintroduced in the well and is removed therefrom on the string in theconventional manner. During operation of the pump the entire assembly issupported on a well head fitting 52 through which the produced fluidsare conducted to a production line 53 through a flowmeter 54.

The pump piston 23 is connected through its rod 24 and its upperconnection element 26 to a suitable line or sucker rod 55 which isprovided with an upper section 56 which acts as a polish rod and passesthrough a suitable liquid seal 57 at the top of the well head assembly52. The length of the polish rod section of the sucker rod or line issufiicient to allow for the full stroke of the pump piston. The flexiblesucker rod or line passes over a pulley 58 and is reeled onto a drum 60by operation of a motor 61 thro gh a transmission assembly indicated.unbalance of the bridge.

'5' generally at 62 and which is located at the well head adjacent thederrick or rig assembly 63 on which the pulley 58 is mounted. In thisarrangement the pump casing is located on the tubing 50 adjacent aselected production zone of the formation, indicated generally at 64,and is centered in the well casing indicated at 65 by the stabilizers27. Further centering devices may be provided if desired; however, theswab cup assembly of FIG. 1 is not employed in this application.

Because the power stroke of the piston is effected only on the upwardmovement thereof, and the piston assembly returns to its lower positionby its own weight assisted somewhat by the vacuum or low pressureexisting in the chamber 15 below the piston, it is not necessary toemploy a rigid sucker rod for driving the piston and flexible rods orlines may be employed. By way of example, the pump may be operated by anylon rope. In other applications where greater loads are required to becarried by the line, a steel wire coated with nylon or other protectiveplastic may be employed.

The motor 61 is arranged to be connected to a suitable source ofthree-phase power indicated at 66 through operation of a controlindicated generally at 67 which includes the starting, stopping andreversing functions of the control system of the motor. The limitswitches 47 and 48 are connected to the control 67 through suitableelectrical leads indicated at 68 and 69, respectively.

In the operation of this system, when a predetermined quantity of liquidhas not been accumulated and the piston has descended to its bottomposition, the motor is stopped by operation of the limit switch 47. Themotor then remains in its inactive condition until liquid hasaccumulated in the chamber 15 to a quantity sufiicient to produce apredetermined tension in the line 56.

This tension in the line produces torque in a shaft 70 in thetransmission 62, the shaft 70 being an intermediate shaft between adrive shaft 71 and a shaft 72 of the drum 60. Connections to the shaft70 are made by a sprocket and chain 73 between the shafts 70 and 71 anda sprocket and chain assembly 74 between the shafts 70 and 72. Thechains 73 and 74 engage sprockets 75 and 76 which are mounted in spacedrelationship and rigidly to the shaft 70 thereby providing a portion ofthe shaft between the sprockets, so that torque is produced between thesprockets and tends to twist this portion of the shaft 70.

The torque produced in the portion of the shaft between the sprockets 75and 76 is-sensed by a suitable strain gauge control system, one form ofwhich is diagrammatically illustrated in FIG. 3. In this controlarrangement four strain gauge elements 77, 78, 79 and 80 are connectedin a bridge to which an input voltage is supplied from a controlassembly indicated generally at 82 through leads 83 connected toopposite terminals of the bridge 84 and 85. The opposite pair ofterminals of the bridge indicated at 86 and 87 are connected by outputleads 88 to the control assembly 82. The leads 83 and 88 are connectedto the shaft through a suitable slip ring assembly indicated generallyat 90 so that the circuits to the rotating parts may be maintainedcontinuously during operation of the system.

The strain gauges 77, 78, 79, and 80 are preferably of the bonded typewhich are suitably cemented or otherwise secured to the shaft portion inpositions such that,

when they are connected in the bridge circuit, any bending or distortionof the gauges due to thrust strains or bending of the shaft will cancelout while the effects of torque in the shaft will be additive and willproduce an This unbalance is proportional to the torsional strain and isemployed by the torque control unit 82 to effect control of the motorcontrol assembly 67 to initiate operation of the motor and raise thepiston 23 when a predetermined torque exists as measured by the torquesensing elements. The

1, amount of torque to which the control is effective for startingoperation of the motor in this manner is selected so that it representsa predetermined load of liquid on the piston 23. This load is selectedso that when the cylinder 15 is substantially full the piston will beoperated to discharge the accumulated liquid through the dischargevalves 21.

The amount of liquid discharged from the pump is measured by thefiowmeter 54 and, when a predetermined amount of liquid has beendischarged which is equal to the volume of the cylinder between thenormal Working positions of the piston, the fiowmeter 54 operates toclose a relay 92. This closes a circuit in the control assembly 67 ofthe motor 61 to stop the motor and reverse it to allow the piston toreturn to its lower position again. In the event the piston 23 shouldoverstroke on its upward movement, the limit switch 48 will effect thestopping of the motor and its reversal.

It will now be apparent that during the operation of the pump the pistonmay be allowed to remain in its low position for long periods of timepending the accumulation of sufiicient liquid to produce the requiredtorque in the control 82 as sensed by the strain gauges 77, 78, 79 andand that, therefore, the motor 61 is required to operate only whensuificient liquid has accumulated in the pump chamber 15 to warrantoperation of the pump. The result of this control system is thus aneconomical use of electric power, short cycling of the pump beingavoided and production being effected at Whatever rate the well isproducing.

It will readily be understood that the control system of FIGS. 2 and 3may be employed with the pump regardless of the manner in which the pumpis connected to deliver the produced liquids to the well head. Thus thecontrol system applies equally to the pump as shown in FIG. 2 and whenemployed to produce directly through the casing as illustrated inFIG. 1. In both of the applications the pumps are actuated throughtension lines or cables which are relatively light as compared with theheavy sucker rods employed with conventional pumps. This light assemblyavoids the necessity of employing amounts of power such as are requiredfor moving heavy sucker rod assemblies.

Furthermore, since the pump assembly of the invention may be providedwith a long pump cylinder or barrel, the usual short stroking of theconventional pump is avoided. The barrel of a pump embodying thisinvention may, for example, vary in length from relatively shortcylinders to cylinders as much as say 300 feet in length. When some ofthe lighter materials such as plastics are employed for the rod or rope,the buoyancy of the material in the produced petroleum liquids rendersthe rod in effect relatively weightless. This is an advantage in thecontrol and facilitates the operation with less power consumption.

The pump of this invention is particularly well suited to the productionof oil wells which are low producers or strippers. Wells such as theseare generally uneconomical and many are abandoned for this reason. Withthe present invention it is possible to operate these Wells economicallysince the pump may stand idle for long periods of time and is operatedonly when suflicient liquid has entered the pump to warrant suchoperation. For example, in a well producing only half a barrel a day thepump chamber could be made capable of holding a barrel of oil and wouldthen stroke only once every two days. It would thus run for a very shortinterval of time during the stroke and would remain idle again foranother two-day period.

In another system of control using essentially the same system as thatof FIG. 2 and a system wherein the line 56 is preferably a light linesuch as a nylon rope, the control can be effected by operating thestrain gauge system in two stages. In the first stage when the motor isreversed to return the piston to its lowermost position the strain gaugeis calibrated so that, when the load comprising the piston, piston rodand line is lost upon bottoming of the piston in the cylinder, thetorque strain gauge control operates the motor to return the piston ashort distance from the bottom and there stops it; the piston thenremains in this stopped position until the predetermined liquid load hasbeen reached as in the previously described modification; thereupon theoperation of the system to pump the liquid is the same as thatheretofore described.

The system illustrated in FIG. 4 is generally similar to thatillustrated in FIG. 2 and corresponding parts have been designatedbytl1e same numerals with the sufiix letter a. The system of FIG. 4 issimilar to that of FIG. 2 in that the return stroke of the piston isinitiated on the outflow of a predetermined quantity of liquid asmeasured by a flowmeter 54a which closes a switch 92a to energize acircuit in the control of the system 67a and reverse the motor so thatthe piston moves downwardly. The length of the downstroke in thisembodiment is determined by providing a measuring control 95 which isset to effectively measure a predetermined length of the tension line56a which is reeled on and off a drum 60a. This control is illustratedin enlarged detail in FIG; 5.

The transmission system for the drum 60a is indicated generally at 96and comprises a gear and sprocket drive from a sprocket 97 driven by themotor 61a through a chain 98 to a sprocket on the drum 6001. A secondchain and sprocket drive including a chain 100 and sprockets 101 and 102is arranged to drive the calibrating control 95. As shown in FIG. 5, thechain 100 drives the sprocket 102 which is mounted on a threaded shaft103 having threads of very low pitch; the shaft has mounted on it atraveling nut 104 which, upon rotation of the shaft, is moved along aguide track 105-. The nut 104 moves away from the sprocket 102 as thepiston of the pump rises, that is, as the line 56a is Wound onto thedrum 60a.

The control includes a normally closed switch 106 which is mounted formovable positioning along the guide 105 and is locked in a positiondetermined by the desired bottom position of the piston. In calibratingthe apparatus the switch assembly 106 is moved to a position so that itis open when the line has been paid out to place the piston in itslowermost desired position. The opening of this switch stops the motor,which thus holds the piston in its bottom position until such time asthe pumping stroke is initiated.

In the system of FIG. 4 the pumping stroke is initiated by a straingauge indicated diagrammatically at 107 and which is connected with thecontrol unit 67a. The strain gauge 107 is responsive to the tension loadin the line 56a and, when a predetermined load has accumulated on thepiston of the pump, the signal from the strain gauge 107 results inoperation of the control to initiate the upward movement of the line 56aby the winding of the line onto the drum 60a. The strain gauge 107 hasbeen indicated diagrammatically as an element in the line 56a; however,it will be understood that the leads to the strain gauge in thisarrangement will be incorporated in the line 56a and carried to suitableslip rings operating from the drum 60a so that the strain gauge may beincluded in the control circuit.

It will now be apparent that during operation of the system illustratedin FIG. 4 the upward stroke of the piston will be initiated by operationof the control in response to the strain gauge 107 whereupon the pistonwill rise and discharge the liquid through the conduit 53a through theflowmeter 54a which, upon discharge of a predetermined quantity ofliquid, will actuate the control 67a to stop the motor 61a and effectits return operation to again lower the piston in the pump. When thepiston has reached a predetermined position as set on the measuringapparatus illustrated in FIG. 5, the switch 106 will be opened and willstop the motor 61a through operation of the control 67a. The pump willthen remain idle until sufficient liquid has again accumulated to effectoperation of the motor under control of the strain gauge 107.

The full details of the control circuitry of the systems illustrated inFIGS. 2 and 4 have not been included since many forms of circuits andsensing elements may be employed to efiect the operation as describedand a detailed illustration and description of the particular controldevices is not essential to an understanding of this invention.

A still further embodiment of the invention is illustrated in FIG. 6which is a view of the upper portion of the derrick designated in thisassembly as 63b, the general arrangement being similar to that of theother figures and the suflix letter b being employed to designate thesame parts. The pulley 58b of this embodiment is hung from the derrick631) on a tension rod indicated at 108 and is held out from the derrickon a rod 109. In this modification the tension in the line 56b is sensedby a strain gauge unit 110 mounted on the tension member 108. Thissensing assembly, including the strain gauge 110, operates inessentially the same manner as that of the strain gauge 107 of themodification of FIG. 4. The remaining elements of the control system maybe the same.

It will readily be understood from the foregoing that the systemprovided in accordance with this invention operating with the pump asillustrated and described provides a simple and effective arrangementfor producing petroleum or other liquids from deep wells, particularlyfrom wells wherein the production is relatively low and economicaloperation is desired. The control elements of the system are such thatvariations in the system, for example stretching of the tension linebetween the piston and the drum, can be compensated by adjustment of thecontrols and do not affect the operation of the system. The system isautomatic and reliable and may be operated over long periods of timewith minimum attendance.

While the invention has been illustrated in connection Wtih specificconstructions and control arrangements, various modifications and otherapplications will occur to those skilled in the art. Therefore, it isnot desired that the invention be limited to the details illustrated anddescribed and it is intended by the appended claims to cover allmodifications which fall within the spirit and scope of the invention.

I claim:

1. A liquid pump for deep well operation and the like comprising anelongated body having a cylindrical chamber therein, a piston in saidchamber, an intake valve at the top of said chamber providingcommunication with the outside above said chamber for admitting liquidto said chamber above said piston, a discharge valve at the top of saidchamber, power means for lifting said piston, means dependent upon theaccumulation of a predetermined quantity of liquid in said chamber abovesaid piston for actuating said power means to lift said piston anddischarge liquid through said discharge valve, and means dependent uponthe discharge of said predetermined quantity of liquid for controllingsaid power means to stop the upward movement of said piston and initiatethe return stroke thereof.

2. A liquid pump for deep well operation and the like as set forth inclaim 1 including a tension line connecting said piston and said powermeans for actuating said piston and wherein said return stroke iseffected by reverse movement of said line and the weight of the pistonassembly.

3. A liquid pump for deep well operation and the like as set forth inclaim 2 wherein said means dependent upon the accumulation of liquid insaid chamber comprises a strain gauge responsive to the strain in saidline.

4. A liquid pump for deep well operation and the like comprising a pumpbody having a cylinder therein and a piston freely movable in saidcylinder between upper and lower positions therein, an inlet valve atthe top of said cylinder for aifording a flow of liquid into the cylinder from the top, a discharge valve at the top of said cylinder, powermeans and a tension line connecting said piston and said power means forlifting said piston to discharge liquid from said cylinder, meansdependent upon the strain in said line produced by the accumulation ofliquid in said cylinder above said piston for initiating the operationof said power means to effect the movement of said piston toward itsupper position, and means associated with said power means for returningsaid piston to the lower portion of said cylinder.

5. A liquid pump for deep well operation and the like comprising a pumpbody having a cylinder therein and a piston freely movable in saidcylinder, an inlet valve at the top of said cylinder for affording aflow of liquid by gravity into the cylinder from the top, a dischargevalve at the top of said cylinder, power means and a flexible tensionline connecting said piston and said power means for lifting said pistonto discharge liquid from said cylinder, control means connected withsaid power means and dependent upon the presence of a predeterminedquantity of liquid in said cylinder above said piston for initiating theactuation of said power means to lift said piston, and means dependentupon the movement of said piston to a high position in said cylinder foroperating said power means to release the tension in said line andafliord downward movement of said piston and the filling of saidcylinder with liquid by gravity flow.

6. A liquid pump for deep well operation and the like comprising a pumpbody having a cylinder therein and a piston freely movable in saidcylinder, means for positioning said body in a well casing, an inletvalve at the top of said cylinder for affording a flow of liquid intothe cylinder from the top, a discharge valve at the top of saidcylinder, means for sealing the well casing to provide a production zoneabout said inlet valve, power means and a tension line connecting saidpiston and said power means for lifting said piston to discharge liquidfrom said cylinder, means dependent upon the strain in said line forcontrolling the movement of said piston, and a liquid discharge zoneabove said pump whereby liquid produced by operation of said pump isdischarged upwardly through said casing.

7. A liquid pump as set forth in claim 6 including means for equalizingthe pressures on the opposite sides of said sealing means for affordingrelease of said seal and removal of said pump on said tension line.

8. A liquid pump as set forth in claim 7 wherein said pressureequalizing means comprises a sleeve valve mounted on said body abovesaid discharge valve and providing communication between said two zones,said sleeve valve being downwardly biased to its closed position, andmeans dependent upon upward movement of said piston to a top positionfor engaging and opening said sleeve valve.

9. A liquid pump as set forth in claim 4 including a production tubingextending upwardly from said body to the well head and wherein saidtension line is positioned within said tubing.

10. A liquid pump as set forth in claim 4 including a piston rod forsaid piston and wherein said tension line is constructed of a syntheticplastic and connects said power means and said piston rod.

11. A liquid pump as set forth in claim 4 wherein said tension linecomprises a synthetic plastic rope and said strain dependent meanscomprises a strain gauge responsive to strain in a load carrying portionof said power means.

12. A liquid pump for deep well operation and the like comprising anelongated body having a cylindrical chamber therein, a piston in saidchamber, an intake valve at the top of said chamber providingcommunication with the outside above said chamber for admitting liquidto said chamber above said piston, a discharge valve at the top of saidchamber, power means for lifting said piston, control means connectedwith said power means and dependent upon the accumulation of apredetermined quantity of liquid in said chamber above said piston forinitiating the actuation of said power means to lift said piston anddischarge liquid through said discharge valve, means including a limitswitch for controlling said power means to stop the upward movement ofsaid piston at a predetermined position and initiate the return movementthereof, and means including a second limit switch actuated uponmovement of said piston to a predetermined lower position for stoppingsaid piston at its lowermost position.

References Cited by the Examiner UNITED STATES PATENTS 244,909 7/ 1881McCartey 103-156 445,962 2/ 1891 Montgomery 103-155 911,609 2/ 1909Purcell 103-156 2,237,394 4/1941 Smith 103-25 X 2,336,083 12/1943 Franz.2,432,271 12/1947 Barifii 73296 X 2,577,479 12/ 1951 Owen l03272,690,713 10/ 1954 Urmann et al. 103-25 2,704,046 3/ 1955 Moraga 73-296X 2,913,910 11/1959 Gillum 103-25 X 2,934,728 4/ 1960 Pleuger 103-25 X2,953,659 9/1960 Edwards. 2,956,511 l0/1960 Morehead 103-212 X 3,046,9047/ 1962 Crow 103-155 3,065,704 11/1962 Hill 103-155 LAURENCE V. EFNER,Primary Examiner.

1. A LIQUID PUMP FOR DEEP WELL OPERATION AND THE LIKE COMRPRISING ANELONGATED BODY HAVING A CYLINDRICAL CHAMBER THEREIN, A PISTON IN SAIDCHAMBER, AN INTAKE VALVE AT THE TOP OF SAID CHAMBER PROVIDINGCOMMUNICATION WITH THE CUTSIDE ABOVE SAID CHAMBER FOR ADMITTING LIQUIDTO SAID CHAMBER ABOVE SAID PISTON, A DISCHARGE VALVE AT THE TOP OF SAIDCHAMBER, POWER MEANS FOR LIFTING SAID PISTON, MEANS DEPENDENT UPON THEACCUMULATION OF A PREDETER-